Lubricant



Patented July 2 5, 1939 UNITED STATES PATENT OFFICE Texas Company, New of Delaware York, N. Y., a corporation No Drawing. Application July 25, 1936,

Serlal No. 92,639 a 10 Claims.

This invention relates to sulfurized lubricants and has to do particularly with sulfur-containing oils suitable for use as cutting oils, gear lubricants and the like.

5 It is an object of the invention to provide an improved sulfurized lubricant containing a-stable added sulfur content having improved properties for uses for which such products are applied.

It is a further object of the invention to provide an improved process for manufacturing sulfurized lubricants through the agency of a sulfur base.

It is also an object of the invention to provide an improved sulfur base for incorporation into ll lubricants in' the manufacturing of sulfurized lubricating compositions.

In practicing the invention, the sulfur base is prepared by reacting sulfuf with naphthenic acids under the influence of heat. The resulta ing sulfurized base is then incorporated into a suitable lubricating medium such as a hydrocarbon lubricating oil, to form an improved lubricant. The naphthenic acids are recovered from petroleum products and preferably those extracted from lubricating distillates. A suitable rade of naphthenic acids is a refined product having a saponification value about 125 or higher. The lubricatingoil may be any well known grade of petroleum lubricating oil. For the preparation of cutting oils, a light lubricating oil having a viscosity of about 70-100 may be used. A heavier lubricating oil, such as cylinder stock, is suitable for the manufacture of'gear' lubricants. Oils having a viscosity intermediate a light oil and cylinder stock, however, may be used if desired.

The sulfur base is prepared by heating sulfur with naphthenic acids to a temperature suflicient to incorporate the sulfur into the naphthenic acids. A temperature of upward of 300 F. and

40 preferably around 400 F. is ordinarily sufficient. 'I have found that best results are obtained by also using a superatmosphei'ic pressure in excess of 'pounds, preferably around 100 pounds; for example, to pounds has been used with suctu cess. The amount of sulfur incorporated in the naphthenic acids is not fixed although I have found that around 5% can be readily incorporated and the rmulting product comprises a satisfactory sulfur base.

lid The sulfur base is readily soluble in the lubrieating oil and may be incorporated therein at temperatures although it is sol advantageous to mix the base with a lubricating" oil while hot. The amount of the base added to f iii the lubricating oil depends on the amount of sulfur desired in the final product. I prefer to have around 1 to 3% sulfur content in the final product. Good results have been obtained with about sulfur content.

The following examples will fully illustrate the invention although the invention is not limited to the specific examples given.

A sulfur base was prepared by mixing 10% sulfur with 90% naphthenic acids having a gravity of 13.1, viscosity at 210 F. of 123 Saybolt Universal, saponiflcation value of 133 and containing 24.5% non-saponifiable matter. The mixture was heated for about 8 hours at a temperature of about 400-420 F. under a superatmospheric pressure of 80-90 pounds. The resulting product, after the removal of unreacted free sulfur, was a bright viscous product with pleasant mineral oil odor. The sulfur content was 5.01%.

A cutting oil was prepared by blending 20% of the above sulfurized naphthenic acids with 80% of pale lubricating oil of about 70 viscosity at F. Tests on the finished cutting oil were asfollows:

Viscosity Saybolt Universal 100 F 157 Sulfur per cent-.. 1.3

Cutting eillciency (speeds 7-70 feet per minute) Good A gear lubricantwas prepared by dissolving 20% of the sulfurized naphthenic acids with 80% cylinder stock having an extreme pressure test of 10 pounds (Timken). The tests on the finished gear lubricant were as follows:

Viscosity Saybolt Universal 210 F Sulfur -per cent" 1.3 Extreme pressure test (Tlmken) pounds +20 According to one method of operation, the sulfurized naphthenic acids are'readded to the lubricating oil from which the naphthenic acids were extracted. Such a cyclic process involves the recovery of the naphthenic acids from a lubricating oil which normally contains naphthenic acids by methods well known in the art, sulfurizing the acids as described herein and the readding of the sulfurized product to the thus refined lubricant in. proper proportions to form the ole-e sired lubricant. The recovery of the naphthenic acids from the lubricating distillate, for example, may be done by extracting with caustic aiiiaii or distilling oi the oil over the alkali, to produce crude sodium naphthenates from which the crude acids may lee separated-by acidification. fidecrude acids are preferahlypurifled by fractional distillation, aeidtreatment etc. A selected free bio v5.1.2

tion most suited for sulfurizing may be subjected to sulfurization and the resultant sulfurized fraction readded to the oil from which the acids were extracted.

The sulfurized lubricants prepared as herein described have the advantagesof a good appearance and odor, relatively high stability against sludge formation and other deterioration, and improved eificiency in operation. The sulfurized lubricants have a tendency to show reduced wear of the parts lubricated and are particularly adapted for high speed operation. The cutting oils are especially characterized by their ability to give satisfactory operations of cutting machines at high speeds, for example as high as '70 feet per minute in pipe threading a 2 inch pipe, whereas lubricants heretofore have been satisfactory at much lower speeds of the order of -60 feet per minute. The gear lubricants tend to have a sticky texture which improves the ability of the lubricants to adhere to the gears and provide a satisfactory lubricating film in addition to extreme pressure characteristics.

While the invention has been described as applicable for the manufacture of lubricants from straight naphthenic acids, it is to be understood that derivatives of naphthenic acids such as esters, for example, the methyl, ethyl, propyl esters, etc., as well as the amids of the acids or their derivatives may be used. These derivatives are contemplated to be within the scope of the invention.

Obviously many modifications and variations of the invention, as hereinbefore set forth, may be made without departing from the spirit and scope thereof, and therefore only such limitations should be imposed as are indicated in the appended claims,

I claim:

1. A mineral oil productv comprising a hydrocarbon lubricating oil admixed with a separately sulfurized base prepared by heating sulfur with naphthenic acids separated from petroleum oil.

2. A cutting oil comprising a light mineral lubricating oil and a small amount of sulfurized naphthenic acids resulting from the reaction under the influence of heat of sulfur with naphthenic acids separated from petroleum oil.

3. A gear lubricant comprising a heavy mineral excess of 125, and then adding said base to a hy I drocarbon lubricating oil.

6. A process for the manufacture of sulfurized lubricants of the class of cutting oils and gear lubricants which comprises heating sulfur with naphthetnic acids separated from petroleum oil at a temperature sufficient to incorporate in the region of 5% of sulfur into the naphthenic acids, then adding about 20% of the resulting product to a hydrocarbon lubricating oil.

7. A process for the manufacture of sulfurized I lubricants which comprises separating naphthenic acids from a mineral lubricating oil, heating the separated naphthenic acids with sulfur to form a sulfur base and readding the sulfur base to said mineral lubricating oil.

8. A sulfurized lubricating oil composition comprising essentially hydrocarbon lubricating oil and 1-3% of added sulfur in the form of a sulfur base resulting from the heating of naphthenic acids with sulfur at temperatures in the region of 9. A cutting oil comprising a mineral lubricating oil having a Saybolt viscosity at 100 F. of about -100, and 13% of added sulfur in the form of a separately sulfurized base resulting.

from the heating of sulfur with naphthenic acids separated from petroleum oil.

. 10. A gear lubricant comprising a cylinder stock admixed with a sufficient proportion of a separately sulfurized base to impart extreme pressure characteristics thereto, said base resulting from the heating of sulfur with naphthetnic acids separated from petroleum oil.

GUS KAUFMAN 

